The Tolkien Quote Database
"I once saw him sitting alone on the top of the Carrock at night watching the the moon sinking towards the Misty Mountains, and I heard him growl in the tongue of bears: "The day will come when they will perish and I shall go back!" That is why I believe he once came from the mountains himself."
Gandalf
J.R.R. Tolkien, Queer Lodgings, The Hobbit